Money Tree - $38 per trials.
or
Flynt Digital - $40 per trial and a special promo for January - $50 per every $9.95 1 month sign up. ( the competition is paying $25 for that kind of sales ).
edited: sorry, it seems you meant pay per click ( ppc ) - I thought you wrote PPS ( pay per sale )
BTW, not sure if that;s a good idea to pay per click to the search engine and rely on pay per click programs, that count 2nd page clicks etc.